1. Field of the Invention
This invention relates to the aiming of a shooting device having aiming sights, and more particularly concerns a lens system which enhances a shooter's ability to see his sights and intended target.
2. Description of the Prior Art
In the case of firearms such as rifles and pistols, aiming is generally achieved by visually aligning a rear sight and a front sight with an intended target. To achieve such alignment, the shooter's eye must attempt to focus on all three components, namely rear sight, front sight and target. Ideally, if all three components were clearly in focus in the shooter's eye, accurate aiming is achieved.
In reality however, it is impossible for the human eye to focus simultaneously on several linearly separated objects such as a rear sight, front sight and distant target. Furthermore, focusing difficulty increases with the shooter's age. Although eyeglasses can improve the shooter's ability to focus upon an object at a specific distance, it generally worsens the ability to focus at other distances. Accordingly, if a shooter, with or without glasses, is focusing upon a distant target, his vision of his rear sight is blurred. Conversely, if the same shooter focuses upon his rear sight, then the target becomes blurred.
Many shooters, in the course of aiming will cause their eye to focus repeatedly and sequentially between rear sight, front sight and target. Such action not only causes eye fatigue, but still falls short of the ideal situation where the sights and target are simultaneously in relatively clear focus.
Standard prescription eyeglasses lenses are generally powered to the quarter diopter, namely 0.25, 0.50, 0.75 and 1.00, etc. The tolerance to which said standard prescription lenses are ground is typically plus or minus an eighth diopter.
Although some of the shooter's visual problems could possibly be resolved by a trained optometrist who would examine the shooter at the target or hunting range, such examination would be expensive.
U.S. Pat. No. 5,726,731 to Toler discloses a system for enabling a shooter to select a specialized eyeglass lens which will improve his ability to see both the sights and target. However, the system involves some cost, or alternatively may involve a fee to an optometrist employing the system. Additional expense is incurred when the appropriate eyeglasses are made by an optometrist. Such cost may be significant if the specialized prescription eyeglasses further incorporate standard features of shooter's glasses such as shatter resistance, glare resistance and special tint for absorption of ultraviolet components of sunlight. Furthermore, the lens selection system of said patent may involve weeks of delay between the time the proper lens is ascertained and receipt of appropriate eyeglasses from the optometrist.
It is accordingly an object of this invention to provide a simple and rapid method for ascertaining an individual shooter's visual needs for focusing on the sights of his firearm and the intended target.
It is another object of the present invention to provide an inexpensive optical device whose characteristics are selected by the method of the foregoing object.
It is a further object of this invention to provide an optical device of the aforesaid nature which can be utilized in association with commonplace shooter's glasses.
These objects and other objects and advantages of the invention will be apparent from the following description.